OpenEuphoria

Re: Text File Comparison

• Posted by rforno at tutopia.com Feb 10, 2002
• 587 views

Please find below a corrected and improved version of my previous algorithm
on the subject.

--Program to show the differences between two files
--Author: R. M. Forno - Version 0.1 - 2002/02/10

function diff(sequence s, sequence t)
    integer i, lens, lent, max, min, a, b, z, n, m, topi
    sequence r, x
    lens = length(s)
    lent = length(t)
    max = lens + lent
    r = {}
    i = 1
    z = 1
    while i <= lens do
 min = max
 topi = lens + 1
 m = i
 while m < topi do
     x = s[m] --Speedwise
     n = min - m + i + z - 1
     if n > lent then
  n = lent
     end if
     for j = z to n do --Search for minimum slack
  if equal(x, t[j]) then
      min = m - i + j - z --Update minimum slack
      topi = min + i --Update upper limit for m
      a = m
      b = j
      exit
  end if
     end for
     m += 1
 end while
 if min < max then
     for k = i to a - 1 do
  r = append(r, {1, k})
     end for
     for k = z to b - 1 do
  r = append(r, {-1, k})
     end for
     r = append(r, {0, a})
     i = a + 1 --Update starting points
     z = b + 1
 else
     exit
 end if
    end while
    for k = i to lens do --Last part
 r = append(r, {1, k})
    end for
    for k = z to lent do
 r = append(r, {-1, k})
    end for
    return r
end function

function read_in(sequence fn)
    sequence s
    object x
    integer f
    s = {}
    f = open(fn, "r")
    if f < 0 then
 puts(2, "Error - cannot open " & fn)
 abort(1)
    end if
    while 1 do
 x = gets(f)
 if atom(x) then
     exit
 end if
 s = append(s, x)
    end while
    return s
end function

procedure out_diff(sequence r, sequence a, sequence b)
    sequence x
    integer n, z
    for i = 1 to length(r) do
 x = r[i]
 n = x[1]
 z = x[2]
 if n < 0 then
     puts(1, "< " & b[z])
 elsif n > 0 then
     puts(1, "> " & a[z])
 else
     puts(1, "  " & a[z])
 end if
    end for
end procedure

--Example of usage

sequence a1, a2, r
a1 = read_in("file1")
a2 = read_in("file2")
r = diff(a1, a2)
out_diff(r, a1, a2)

----- Original Message -----
From: <petelomax at blueyonder.co.uk>
To: "EUforum" <EUforum at topica.com>
Sent: Friday, February 08, 2002 9:40 PM
Subject: Text File Comparison



Looking for a source file comparison utility - must be written in
Euphoria or a source I can translate.

Thinking out loud, it seems non-trivial to report the smallest
possible number of changed lines, which is what I want.

At the moment I'm struggling with DOS fc utility but I'd like an
output similar to:

function fred()
sequence result
>integer i
result={}
< for i = 1 to 10
< if skip[i]=0 then
> i=1
> while i <= 10
> if skip[i]>0 then
> i+=skip[i]
> else
result&=i
> i+=1
end if
< end for
> end while
return result
end procedure

whereby ">" lines have been added & "<" removed.

Hopefully someone out there in the Linux world has the source of
"diff" I think it is which I suspect handles this alot better than I
could starting from scratch.

Using fc I get alot of false realigns on "end if" causing the output
to be much larger than it ought to be. Raw performance is unlikely to
be an issue.

Pete